Is “Sent by the Later Ruler to appease Wei Yan” true?

In the official history Records of the Three Kingdoms, Book of Shu, Biographies of Liu, Peng, Liao, Li, Liu, Wei, and Yang, it is recorded that when Wei Yan and Yang Yi each accused the other of rebellion, the Later Ruler asked Jiang Wan and Dong Yun, and 'Wan and Yun both vouched for Yi and suspected Yan,' with no mention of Dong Yun being sent to appease. In the novel Romance of the Three Kingdoms, Chapter 105, after hearing the report, the Later Ruler says: 'If so, let Dong Yun take the credentials and go to explain and console, using kind words to soothe him.' This is a plot that the novel has transplanted or rewritten.